Expert systems are knowledge based computer applications that simulate decision making process. A typical expert system is made up of a set of rules that are designed to provide solutions to a specific class of problems. One type of rule is composed of an if-clause and a then-clause. The if-clause specifies the condition under which the rule is executed or “fired” and the then-clause specifies the action resulting from the execution of the rule. Accordingly, each rule describes a state of the expert system that requires a particular action.
One type of expert system is a data driven, forward chaining rule-based system that applies the rules of the system to the data in an integrated database, in response to an initial event in the database, until a final decision is reached. Specifically, this type of system reacts to the initial event by searching the system's rule set until it finds a rule that has a true if-clause. The system then executes the then-clause of the rule, updating the data in the database and/or causing other external or internal changes in the system. The process is repeated after each update and the conditions of the rules are re-evaluated until none of the rules has a true if-clause.
The number of rules in rule-based system can range from a few to several thousand, or more, for more complex systems. Sometimes more than one rule in a system may be in condition for execution, (that is, “true”) given the state of the database. Further, the order of their execution would significantly affect the output of the system. Therefore, it is imperative in the design of a rule-based expert system to manage rules themselves for the system to function properly. As expert systems become more complex, the number of rules in the systems continues to grow. The increased number of rules translates into more complexity and dependencies between the rules. Consequently, it is becoming more difficult, if not impossible, to resolve rule specific system failures in a sophisticated system.
The present invention addresses this need.